The aforenoted co-pending application disclosed a very simple but highly effective way of determining engine load and controlling an engine control system in response to the determined load to improve engine operation. That method and apparatus, because of its simplicity, permits incorporation in relatively small and low production volume engines as used in motorcycles, motor scooters and like engine applications.
In addition to controlling an engine system to improve its operation, transient conditions frequently are considered to fine tune engine operation. For example, in addition to instantaneous load or operator demand, a change in either load or demand may require a modification of the system control to provide smoother and more efficient operation.
For example, ignition control is generally set in response to operator demand, often determined by throttle position. The basic timing determined by the throttle position could advantageously improved by also considering the state of acceleration or deceleration. This can be done by determining the rate of change in the degree of throttle opening. In a vehicle such as a motorcycle, to prevent a wheelie (the front wheel being raised off of the ground) when the throttle is rapidly opened at the time of starting, the output is lowered, and in normally accelerated running, the output is increased to improve the acceleration performance. In such cases, the output can be decreased by retarding the ignition timing. On the other hand under other conditions, the output can be increased by advancing the ignition timing.
A conventional arrangement for determining acceleration and deceleration uses a throttle position sensor for detecting the throttle opening and a throttle position detecting circuit connected to the throttle position sensor. Also there is provided a circuit for obtaining the rate of change in the throttle position.
However, using a throttle position sensor and a throttle position detecting circuit that also determines the rate of change in throttle position increases the number of components and makes the control system complicated. On top of that, the components are expensive and increase the vehicle price. In small vehicles in particular, the space around the engine is limited and so the layout of components is also a problem. This sometimes results in that there is no space for the throttle position sensor or, if the throttle position sensor is installed, the layout of other components is greatly restricted.
Therefore it is a principle object of the invention to provide an improved engine system control method and apparatus based on operator demand and rate of change in demand that reduces not only the number of components but also decreases the complexity of the electronic system.
It is a further object of the invention to provide an improved engine system control method and apparatus based on operator demand and rate of change in demand that does not require a throttle position sensor.